2 files changed, 55 insertions(+), 4 deletions(-)

M Makefile
M fs/xcomp/arm/rpi/kernel.fs

@@ 45,6 45,10 @@ rpi.img: dusk $(ALLSRCS)
 	dd if=/dev/zero of=$@ bs=1K count=1
 	./dusk < buildrpi.fs
 
+.PHONY: rpirun
+rpirun: rpi.img
+	qemu-system-arm -M raspi1ap -serial stdio -display none -kernel rpi.img
+
 .PHONY: run
 run: dusk
 	stty -icanon -echo min 0; ./dusk ; stty icanon echo

@@ 3,13 3,60 @@
 \ For RPI model 1A
 $20000000 const MMIO_BASE
 $200000 const GPIO_BASE
+$94 const GPPUD
+$98 const GPPUDCLK0
 $1000 const UART0_BASE
+$00 const UART0_DR
+$04 const UART0_RSRECR
+$18 const UART0_FR
+$20 const UART0_ILPR
+$24 const UART0_IBRD
+$28 const UART0_FBRD
+$2c const UART0_LCRH
+$30 const UART0_CR
+$34 const UART0_IFLS
+$38 const UART0_IMSC
+$3c const UART0_RIS
+$40 const UART0_MIS
+$44 const UART0_ICR
+$48 const UART0_DMACR
+$80 const UART0_ITCR
+$84 const UART0_ITIP
+$88 const UART0_ITOP
+$8c const UART0_TDR
 
 $8000 to binstart
 0 align4 here to org
 r0 MMIO_BASE i) mov, \ r0 = MMIO_BASE
 r0 r0 GPIO_BASE i) add, \ r0 = GPIO_BASE
-r0 r0 UART0_BASE i) add, \ r0 = UART0_BASE
-r1 'X' i) mov,
-r0 r1 str,
-$eafffff8 , \ hardcoded "b -8"
+r2 r0 UART0_BASE i) add, \ r2 = UART0_BASE
+\ Disable UART0
+r3 r2 UART0_CR i) add, r1 0 i) mov, r1 r3 str,
+\ Disable pull up/down for all GPIO pins & delay for 150 cycles.
+r3 r0 GPPUD i) add, r1 0 i) mov, r1 r3 str,
+\ TODO: add delay
+\ Disable pull up/down for pin 14,15 & delay for 150 cycles.
+r3 r0 GPPUDCLK0 i) add, r1 $c000 i) mov, r1 r3 str,
+\ TODO: add delay
+\ Write 0 to GPPUDCLK0 to make it take effect.
+r3 r0 GPPUDCLK0 i) add, r1 0 i) mov, r1 r3 str,
+\ Clear pending interrupts.
+r3 r2 UART0_ICR i) add, r1 $700 i) mov, r1 r1 $ff i) add, r1 r3 str,
+\ Set integer & fractional part of baud rate.
+\ Divider = UART_CLOCK/(16 * Baud)
+\ Fraction part register = (Fractional part * 64) + 0.5
+\ Baud = 115200.
+\ Divider = 3000000 / (16 * 115200) = 1.627 = ~1.
+r3 r2 UART0_IBRD i) add, r1 1 i) mov, r1 r3 str,
+\ Fractional part register = (.627 * 64) + 0.5 = 40.6 = ~40.
+r3 r2 UART0_FBRD i) add, r1 40 i) mov, r1 r3 str,
+\ Enable FIFO & 8 bit data transmission (1 stop bit, no parity).
+r3 r2 UART0_LCRH i) add, r1 $70 i) mov, r1 r3 str,
+\ Mask all interrupts.
+r3 r2 UART0_IMSC i) add, r1 $700 i) mov, r1 r1 $f2 i) add, r1 r3 str,
+\ Enable UART0, receive & transfer part of UART.
+r3 r2 UART0_CR i) add, r1 $300 i) mov, r1 r1 $01 i) add, r1 r3 str,
+
+
+r3 r2 UART0_DR i) add, r1 'X' i) mov, r1 r3 str,
+$eafffffe , \ hardcoded "b -2"